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one aspect of the international space

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station's mission is to find out how the

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human body reacts to spending a long

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period of time in weightlessness as

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future astronauts will do on missions to

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mars and other destinations out into the

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solar system there is an experiment

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about to begin on the station that's

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focusing on the impacts to the human

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heart looking at potential changes to

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heart muscle cells

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recently my colleague pat ryan spoke

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with arun sharma of the stanford

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university school of medicine one of the

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co-investigators of the experiment known

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as heart cells and started by asking him

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to explain what negative effects to the

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human heart have been seen in astronauts

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after long-duration space missions

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right so it's been pretty well

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established by a number of studies that

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have come out over the recent years that

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the heart actually changes shape on the

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organ level

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so actually over a long-term exposure to

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microgravity the heart assumes more of a

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spherical shape as opposed to normally

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fist-like shape that it has a ground

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side

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and this is something that happens over

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a period of few weeks and usually that

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shape returns to normal after the

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astronauts return ground side in

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addition there is some

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somewhat of a muscle mass loss or muscle

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atrophy that happens as a result of

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long-term exposure to microgravity the

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heart and the other muscles in the body

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simply don't have to do as much work and

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so therefore to compensate they actually

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reduce some of their muscle mass

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does the change in shape impact the

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heart's efficiency

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it usually does not because it is not at

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a substantial enough level

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on orbit to do so

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is there a way to build back up the mass

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that it's lost i mean we do exercises

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for astronauts to try to recover other

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muscles that are impacted by

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weightlessness

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absolutely so the heart of course is

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just another muscle and it can be

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trained as well so you know once when

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the astronauts do their regular

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exercises on orbit their the heart will

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also

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uh be able to restore some of that lost

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muscle mass although the heart is

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actually a very unique and a very

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interesting organ because after

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something that does damage to the heart

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say a heart attack it actually does not

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replace a lot of its lost cells so for

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example a number of the other tissues in

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the body such as the skin have a really

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strong regenerative capacity

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but once heart cells are lost it's very

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difficult for them to come back

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i understand that you have to keep human

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heart cells in culture in order to study

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them in space

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so you and your colleagues have found a

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way to do that because doing it is a

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difficult thing you found a way to uh

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to do that in order to get the

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experiment samples to study explain what

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that process is

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absolutely so it's pretty tough to

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culture primary human heart tissue or

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human heart tissue from

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patients for a very long period of time

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our lab and other labs around the world

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are trying to figure out ways to keep

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these cells alive long-term in culture

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but so far we've only been able to do so

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for two to three weeks

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but recently over the last 10 years or

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so there have been revolutionary

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advances in the field of stem cell

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biology and this has enabled us to

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actually create heart cells from a type

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of stem cell population called an

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induced pluripotent stem cell or ipsc

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and to do this we basically take a small

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sample of a patient's own skin or blood

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cells usually white blood cells and we

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can reprogram these white blood cells

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into a stem cell-like state after about

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a one month long process

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and once those ipscs those induced

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pluripotent stem cells are created we

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can turn them into really whatever cell

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type we're interested in such as a brain

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cell liver cell skin cell and since

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we're a cardiovascular research

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institute we're interested in heart

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cells

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and so the protocol that we can actually

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use to create these heart cells from

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these

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ipsc stem cells is about a two week long

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process but at the end of the road we

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actually get these visually contracting

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these beating heart cells that you can

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see visually contract under a microscope

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or sometimes with your naked eye

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and these are the cells that you're

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about to launch to the space station to

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to study

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explain what happens once you get them

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to orbit how how long are they there

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what's the process are the human crew

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members helping

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exactly so we will be utilizing these

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ipsc derived heart cells as our model

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system to study the effects of

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microgravity on single cell function on

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heart function

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unlike primary human heart tissues these

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cells can actually survive for a very

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long time in cell culture so we've

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actually been able to grow them for

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longer than a year in our cell culture

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dishes

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and so once these cells are actually

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launched into orbit they'll be

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maintained on orbit for about one month

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in particular by dr kate rubins who is

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is now at the international space

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station and what dr rubins will be doing

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is changing the nutrients on these cells

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on a weekly basis

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in addition she'll also be looking at

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changes in cell shape size beating rates

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uh these are some of the things that

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she'll be helping us out with

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and then they're gonna be brought back

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to earth for you to study uh what are

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you looking for when you get these

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samples back in the lab

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yeah so we actually will have a parallel

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set of samples round side controls

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which will compare our space flown

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samples once they actually return to the

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lab

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and this is important because we'll be

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able to see what are the exact what is

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the impact of microgravity in particular

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on changing

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cells size cell shape

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cell beating rates and also another

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factor gene expression we want to be

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able to see what's the effect of

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microgravity on alterating altering the

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gene expression of these space flown

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heart cells

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and this is by is comparing the two the

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cells that have been to space versus the

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ones that have stayed on earth

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exactly so we'll be comparing the ground

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side samples to our space flown samples

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would you imagine that i mean what is it

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you're trying to find could your results

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have some impact for astronauts as well

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as people with heart issues on earth

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potentially definitely yes i definitely

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think there is some application for

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regenerative medicine ground side as

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well

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as i mentioned earlier the heart is a

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really unique organ in that it has a

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very limited ability to regenerate

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itself and so we're always looking for

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novel new ways that we might be able to

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restore heart function after injury such

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as a heart attack

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and we really don't know what's the

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effect of microgravity on the single

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heart cell but we have a hypothesis that

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maybe

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this uh unique stimulus will be able to

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enhance cell division in a way that's

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not really possible ground side and so

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we're really excited to be able to use

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the international space station as a

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really unique resource and as a way to

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access a an environment that's not

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available here on earth it'll be

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interesting to uh to see what results

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you get thanks for taking a few minutes

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to explain what you're what you're

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working on

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no problem thank you for having me arun

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sharma of the stanford university school

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of medicine is one of the

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co-investigators on the experiment heart